Numerical investigation of multi-layer multi-track cold spray additive manufacturing with an improved SPH method
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Cold spray additive manufacturing (CSAM) is a new solid-state manufacturing technique involving complex phenomena like high-speed impacting of micro-powders, jet generation, large material deformations and phase changes. The CSAM process is hard to simulate in detail, and the underlying coating mechanisms, especially for multi-powders CS, have not been well understood yet. As a Lagrangian and particle-based discretization technique, the smoothed particle hydrodynamics (SPH) method offers unique advantages in treating large deformations and capturing moving interfaces encountered in CSAM simulations [1, 2]. We present an improved SPH approach for implementing three-dimensional particle models in the multi-layer multi-track CS analysis. The kernel gradient correction (KGC), adaptive smoothing length and the constitutive model are integrated into the improved SPH framework. The contour profile and width thickness ratio of the deformed powder obtained by the present simulation are very close to the experimental data. The bonding behaviors in CS with dissimilar materials are explained, where the critical velocities for different materials are specified. Furthermore, coating behaviors in CS with different layers and tracks of powders are comprehensively analyzed. The particle sizes and configurations have significant influences on the coating behaviors. We will also identify some typical deformation parameters of the powders track with regard to an increasing impacting velocity. With the present numerical model, a larger scale multi-layer multi-track CSAM can be conducted with the predicted parameter windows, providing room for improvement in additive manufacturing operations.